The present invention relates to a document conveying circuit for use in a facsimile system, and in particular to a document conveying circuit capable of manually conveying a document.
In general, a facsimile system reads a document with a scanner while conveying automatically the document by the rotation of a motor. An example of document conveying by rotation of a motor will be explained with reference to a conventional circuit diagram shown in FIG. 1.
Referring to a configuration of FIG. 1, the known document conveying circuit includes: a stepping motor 2 for rotating a conveying roller 1; a stepping motor controller SMC 3 for controlling stepping motor 2; a sensor controller 5 for obtaining a desired pictorial image signal by controlling a sensor 4 hereinafter described; a sensor 4 for reading the document 8 by means of reflected light of a light source 7 under the control of sensor controller 5; and a picture signal processor 6 for processing the output received from sensor 4.
It will be explained about an operation in a copy mode which is performed at the regular conveying speed of a document according to above-described configuration, in the following discussion.
Firstly, an output signal "a" of the stepping motor controller 3, as shown in FIGS. 2A to 2D, drives the stepping motor 2 and renders the conveying roller 1 to convey the document 8 by one line (1/7.7 mm or 1/3.85 mm) for a period of time t1, and the sensor 4 is driven by a sensor trigger signal "b" provided by the sensor controller 5. Sensor trigger signal "b" is like the wave forms in FIGS. 2E and 3A, and the document is read in by accumulating the reflecting light for the period corresponding to the time t1 until the next sensor trigger signal "b" is produced.
When a second sensor trigger signal "b" for starting reading of the next line is produced, image information being accumulated is transmitted into one or two internal shift registors of the sensor 4, the sensor driving clock "c" provided by the sensor controller 5 transmits the image signal transmitted into these internal shift registers to the picture processor 6 by one picture element, one by one, through an output line "e" of the sensor. Wave forms of FIGS. 3B and 3C being respective wave forms of driving clock "c" from the sensor 4, when the shift register is one in number, it appears with double frequency, and wave form of FIG. 3E is the image information applied to the picture signal processor 6 through the output line "e" of the sensor 4. A wave form of FIG. 3D is a reset signal inputted into the sensor 4 through a line "d" which is for clearing energy of the picture element transmitted before receiving energy with respect to the next picture element.
Picture signal processor 6 counts a number of inputted picture element signals and takes only a necessary part thereof. Further, when a third sensor trigger signal is produced on the line "b" the light information starts to be accumulated with respect to a third line L3 of the document and, with the same method as aforementioned, the image signal with respect to second line L2 is transmitted to the picture signal processor 6 through the output line "e" of the sensor 4.
The aforementioned system has a problem that the apparatus becomes larger in its size because it requires various supplementary parts such as a conveying roller 1 and a stepping motor 2, a stepping motor controller 3, a gear device for transmitting the motive power of the stepping motor 2 to the conveying roller 1, and the like.